The present invention relates to a displacement absorption piping joint capable of eliminating a trouble which occurs if, for example, a plurality of concrete pavement slabs are arranged adjacent and opposite one another, i.e., a trouble that pipe members, a cable or the like arranged to penetrate between the connected end faces of the adjacent concrete pavement slabs are damaged as a result of the relative displacement of the positional relationship between the concrete pavement slabs caused by the expansion and contraction of the concrete pavement slabs due to temperature change, an external stress or the like.
A concrete structure such as the runway, taxiway or apron of an airport, a concrete structure such as a road or a large-scale concrete or asphaltic structure such as a building, is often constructed by connecting a plurality of structural elements such as pavement slabs each having a required shape or the like. Since a positional shift or a displacement tends to occur between the connected end faces of the adjacent structural elements such as pavement slabs or the like constituting the large-scale structure due to the expansion and contraction of the structural elements, an external stress or the like, measures have been taken to prevent the damage of internal piping and wiring resulting from the positional shift or the like.
When constructing an airport runway, for example, an operation for arranging a plurality of PC pavement slabs each having a width of 7.5 m, a length of 100 m and a predetermined thickness on a field foundation course portion (such as roadbed) to be adjacent one another is carried out. That is, a large-scale structure (or runway) having a plurality of pavement slabs arranged to be adjacent one another is completed by sequentially executing pavement slab manufacturing steps of arranging a rectangular form on the field foundation course portion, filling and then hardening a material such as concrete for each pavement slab.
Meanwhile, if wires such as cables are provided inside the runway, cable wiring protection pipes are provided (or embedded) in the respective pavement slabs in advance and the end portions of the pipes exposed to the connection end faces of the pavement slabs adjacent one another are communicated and connected with one another. Thereafter, cables are inserted into each pipe, thereby completing wiring.
FIG. 10(a) is a perspective cross-sectional view showing a state in which the pavement slabs constituting the runway are provided to be continuous to one another, and FIGS. 10(b) and 10(c) show a piping structure on the connected end faces of the pavement slabs. Rectangular pavement slabs 2, for example, are arranged on a foundation course portion 1 such as a roadbed to be adjacent one another. An embedded lighting unit 3, for example, is embedded in the upper surface of each pavement slab and a cable 5 for supplying electric power to each lighting unit 3 is inserted into a pipe member 4 embedded and provided in each pavement slab 2.
As the pipe member 4, a bellows-shaped flexible pipe member made of a metallic material such as stainless or a steel product is mainly employed since it is advantages in that a piping path can be arbitrarily selected. To couple the pipe members 4 to each other on the connection end faces 2a (joints) of the pavement slabs 2, the openings 4a on the end portions of the respective pipe members 4 exposed to the respective connection end faces 2a are directly coupled to each other.
As shown in FIG. 11, each pavement slab 2 is completed by filling concrete in the form 6 and hardening the concrete while the form 6 is being fixed to the upper surface of the foundation course portion 1. Before an operation for filling the concrete is carried out, the pipe members 4 and the base portions of the lightning units 3 are positioned at predetermined points, respectively.
Meanwhile, the flexible pipes 4 are slightly expansion-deformed mainly in axial direction in response to loads or stresses applied to the pavement slabs, thereby exhibiting a function of slightly absorbing the loads or the like and protecting the internal cable 5. However, on the connection end faces 2a shown in FIG. 10(b), the flexible pipes 4 are simply connected to each other. Owing to this, if the positions of the adjacent pavement slabs 2 are relatively shifted in the plane direction of the connection end faces indicated by arrows as shown in FIG. 10(c), then the positions of the openings 4a on the both end portions are shifted in the plane direction, with the result that a shearing force generated on the both connection end faces 2a is applied to the cable 5 in the pipes and the cable 5 tends to be broken.
Further, even if the flexible pipe members 4 are provided not by connecting the mutual end portions of the pipes 4 but by allowing mutual bellows portions to spread across the connection end faces 2a of the two pavement slabs, the flexible pipes and the internal cable tend to be cut off due to a shearing force generated by the relative movement of the two connection end faces 2a as in the case of FIG. 10.
Thus far, no joint having a function of protecting pipe members provided to spread across the connection end faces of two structural elements from being damaged by a shearing force or the like generated between the connection end faces, has been developed. Due to this, the pipe members spreading across the connection end faces as well as the cable tend to deteriorate in a relatively short period of time, thereby requiring frequent replacement operations. Further, conventionally, it has been only the method to repair deteriorated pipe members by excavating the joint portions of the pavement slabs and thereby partially exposing the piping elements. Since this repair method requires an operation accompanied by labor and cost, it has been demanded to improve this respect.
It is an object of the present invention to provide a displacement absorption piping joint capable of eliminating a trouble which occurs if a plurality of concrete pavement slabs, for example, are continuously arranged on a roadbed with the end faces of the slabs opposite one another so as to construct an airport runway, i.e., a trouble that pipe members, a cable or the like arranged to penetrate between the connected end faces of the adjacent concrete pavement slabs are damaged by a shearing force due to the relative displacement of the positional relationship between the concrete pavement slabs caused by the expansion and contraction of the pavement slabs due to temperature change or the like, an external stress such as a load or the like.
In particular, the piping joint of the present invention is applicable to a case of protecting pipe members provided to spread across two structural elements, which are not limited to concrete structural elements such as concrete pavements, or a wire such as a cable inserted into the pipe members from a searing force generated by the relative displacement of the structural elements.
It is still more another object of the present invention to provide a piping joint capable of largely securing the movement quantities of two pipe members corresponding to the displacement quantities of structural elements despite its compact shape.
To obtain the above objects, the present invention according to claim 1, wherein a displacement absorption piping joint communicating and connecting end portions of pipe members respectively embedded into two structural elements adjacent each other and having connection end faces displaced relatively to each other, with each other on the connection end faces of the both structural elements, wherein the piping joint has a fixed unit fixedly embedded into the connection end face of one of the structural elements while a front end face side of the fixed unit is being exposed, and a movable unit supported by the fixed unit to be displaceable along a plane direction of the connection end faces; the pipe member provided within the one structural element is communicated and connected with the fixed unit, and the other pipe member provided within the other structural element is communicated and connected with the movable unit, thereby holding the both pipe members in the fixed unit in a communicated state; and a stress applied to the both pipe members due to relative displacement of the connection end faces of the both structural elements in the plane direction is absorbed and removed by a displacement action of the movable unit displaced relatively to the fixed unit in the plane direction.
By thus constituting the piping joint, the respective pipe elements arranged to spread across the connection end faces of the two structural elements, which are displaced relatively to each other, can be displaced independently of each other to follow the displacement of the structural elements. It is, therefore, possible to effectively prevent the damage of the pipe members and the like resulting from the fact that the pipe members cannot flexibly follow the displacement of the structural elements. According to the present invention, for the purpose of realizing such a damage occurrence prevention structure, the fixed unit is embedded into one of the structural elements, the movable unit is supported by the other structural element and also the both units are connected to the respectively corresponding pipe members. It is, therefore, possible for the piping joint to exhibit an excellent advantage of preventing the deterioration of the pipe members despite its simple constitution.
According to claim 2 of the present invention, wherein the fixed unit has a hollow box type case having a pipe member connection portion detachably connecting the pipe members on a rear surface and having an open front surface, a surface plate fixed to a front surface of the case through a plate packing so as to close the open front surface of the case, and elongate holes formed to penetrate the flat packing and the surface plate, respectively; and in that the movable unit has a slide base arranged movably into the case closed by the flat packing along the plane direction and having a screw hole formed to penetrate the slide base so as to fix one end of a coupling pipe, a bearing-added elastic urging member arranged between the slide base and an inner bottom of the case so as to elastically press-contact the slide base with an inner surface of the flat packing, the coupling pipe having one end fixedly screwed with the screw hole of the slide base and the other end thereby penetrating the respective elongate holes and protruding forward, a sealing plate screwed with a screw portion on an outer periphery of the coupling pipe and thereby sealing the elongate hole formed in the surface plate, and a nut screwed with the outer periphery of the coupling pipe so as to fix the sealing plate.
By thus constituting the piping joint, it is possible for the piping joint to connect the pipe members embedded into the two adjacent structural elements, respectively, with one another on the connection end faces in a relatively movable manner, and it is possible to protect the pipe members and a wiring provided in the pipe members by displacing the respective pipe members to follow the displacement of the connection end faces of the both structural elements in the plane direction, despite its quite simple constitution.
According to claim 3 of the present invention, wherein the open front surface of the hollow box type case is closed by the surface plate through the flat packing, thereby forming a space between the surface plate and the inner bottom of the case, the space exhibiting an absorbing effect to prevent breakage when the movable unit is displaced relatively to the fixed unit if a wire is penetrated and provided in the coupling pipe from the pipe member connection portion of the case through the space.
By thus constituting the piping joint, the respective pipe elements embedded into the two adjacent structural elements, respectively, are communicated and connected with each other not by being directly coupled to each other by through the space. It is, therefore, possible to secure a large movable space in the space for a wire penetrated into and spread across the respective pipe members. The movable range of the wire provided in the respective pipe members is determined according to the relationship between the inside diameters of the pipe members and the outside diameter of the wire. According to the present invention, since the space exists between the end faces of the both pipe members and this space is located on the relative displacement plane of the connection end faces of the two structural elements, a large movable range is secured for the wire along the displacement plane of the connection end faces, whereby the wire is free from receiving a shearing force resulting from the displacement of the connection end face.
According to claim 4 of the invention, wherein the structural elements are applicable to connections of not only concrete pavement but also all types of structural elements.
The piping joint of the present invention is applicable to a plurality of structural elements having the connection end faces adjacent each other and displaced relatively to each other. If concrete pavement slabs are selected as these structural elements, pipe members and a wire provided to spread across two adjacent structures can be effectively protected from the damage resulting from the relative movement of the both structural elements in longitudinal, lateral and slant directions in concrete structures such as a runway, a taxiway and apron on an airport, a road or the like.